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Mikhemar, Mohyee, David Murphy, Ahmad Mirzaei i Hooman Darabi. "A Cancellation Technique for Reciprocal-Mixing Caused by Phase Noise and Spurs". IEEE Journal of Solid-State Circuits 48, nr 12 (grudzień 2013): 3080–89. http://dx.doi.org/10.1109/jssc.2013.2283758.
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WATANABE, Koji, Koji WADA, Tomoshi YOKOYAMA i Masami HIRATA. "STATIC AXIAL RECIPROCAL LOAD TESTS FOR SOIL-CEMENT MIXING WALL USED AS PERMANET PILES". Journal of Structural Engineering B 68B (2022): 345–52. http://dx.doi.org/10.3130/aijjse.68b.0_345.
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Chandler, Jocelyn B., Alexa J. Siddon, Parveen Bahel, Richard Torres, Henry M. Rinder i Christopher A. Tormey. "Modified approach to fibrinogen replacement in the setting of dysfibrinogenaemia". Journal of Clinical Pathology 72, nr 2 (21.11.2018): 177–80. http://dx.doi.org/10.1136/jclinpath-2018-205438.
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Most fibrinogen replacement strategies focus on quantitative deficiencies. A thrombin time (TT) mixing study helped to assess qualitative defects caused by dysfibrinogens. Plasma samples were collected from non-anticoagulated subjects (n=6) meeting laboratory criteria for suspected dysfibrinogenaemia (TT > 22 s; fibrinogen activity <180) and from a control group. TT mixing studies were performed on subject plasma with increasing volumes of pooled normal plasma at 1:2, 1:4 and 1:5 dilutions. No subjects with dysfibrinogenaemia demonstrated a complete TT correction at 1:2, but 50% corrected at 1:4 and 100% at 1:5 dilution. Based on these data, a correction factor (CF), defined as the reciprocal dilution yielding complete correction, was incorporated into our clinical practice formula for fibrinogen dosing in patients with dysfibrinogenaemias. Our study incorporates TT mixing studies for assessment of dysfibrinogens. The addition of a mix-derived CF to classical formulae may better approximate dosing in patients with dysfibrinogenaemia.
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Bharmoria, Pankaj, Krishnaiah Damarla, Tushar J. Trivedi, Naved I. Malek i Arvind Kumar. "A reciprocal binary mixture of protic/aprotic ionic liquids as a deep eutectic solvent: physicochemical behaviour and application towards agarose processing". RSC Advances 5, nr 120 (2015): 99245–52. http://dx.doi.org/10.1039/c5ra22329f.
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Angarita, Belcy K., Rodolfo J. C. Cantet, Kaitlin E. Wurtz, Carly I. O’Malley, Janice M. Siegford, Catherine W. Ernst, Simon P. Turner i Juan P. Steibel. "Estimation of indirect social genetic effects for skin lesion count in group-housed pigs by quantifying behavioral interactions1". Journal of Animal Science 97, nr 9 (wrzesień 2019): 3658–68. http://dx.doi.org/10.1093/jas/skz244.
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Abstract Mixing of pigs into new social groups commonly induces aggressive interactions that result in skin lesions on the body of the animals. The relationship between skin lesions and aggressive behavioral interactions in group-housed pigs can be analyzed within the framework of social genetic effects (SGE). This study incorporates the quantification of aggressive interactions between pairs of animals in the modeling of SGE for skin lesions in different regions of the body in growing pigs. The dataset included 792 pigs housed in 59 pens. Skin lesions in the anterior, central, and caudal regions of the body were counted 24 h after pig mixing. Animals were video-recorded for 9 h postmixing and trained observers recorded the type and duration of aggressive interactions between pairs of animals. The number of seconds that pairs of pigs spent engaged in reciprocal fights and unilateral attack behaviors were used to parametrize the intensity of social interactions (ISI). Three types of models were fitted: direct genetic additive model (DGE), traditional social genetic effect model (TSGE) assuming uniform interactions between dyads, and an intensity-based social genetic effect model (ISGE) that used ISI to parameterize SGE. All models included fixed effects of sex, replicate, lesion scorer, weight at mixing, premixing lesion count, and the total time that the animal spent engaged in aggressive interactions (reciprocal fights and unilateral attack behaviors) as a covariate; a random effect of pen; and a random direct genetic effect. The ISGE models recovered more direct genetic variance than DGE and TSGE, and the estimated heritabilities (h^D2) were highest for all traits (P < 0.01) for the ISGE with ISI parametrized with unilateral attack behavior. The TSGE produced estimates that did not differ significantly from DGE (P > 0.5). Incorporating the ISI into ISGE, even in a small dataset, allowed separate estimation of the genetic parameters for direct and SGE, as well as the genetic correlation between direct and SGE (r^ds), which was positive for all lesion traits. The estimates from ISGE suggest that if behavioral observations are available, selection incorporating SGE may reduce the consequences of aggressive behaviors after mixing pigs.
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Löptien, Ulrike, i Heiner Dietze. "Reciprocal bias compensation and ensuing uncertainties in model-based climate projections: pelagic biogeochemistry versus ocean mixing". Biogeosciences 16, nr 9 (6.05.2019): 1865–81. http://dx.doi.org/10.5194/bg-16-1865-2019.
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Abstract. Anthropogenic emissions of greenhouse gases such as CO2 and N2O impinge on the Earth system, which in turn modulates atmospheric greenhouse gas concentrations. The underlying feedback mechanisms are complex and, at times, counterintuitive. So-called Earth system models have recently matured to standard tools tailored to assess these feedback mechanisms in a warming world. Applications for these models range from being targeted at basic process understanding to the assessment of geo-engineering options. A problem endemic to all these applications is the need to estimate poorly known model parameters, specifically for the biogeochemical component, based on observational data (e.g., nutrient fields). In the present study, we illustrate with an Earth system model that through such an approach biases and other model deficiencies in the physical ocean circulation model component can reciprocally compensate for biases in the pelagic biogeochemical model component (and vice versa). We present two model configurations that share a remarkably similar steady state (based on ad hoc measures) when driven by historical boundary conditions, even though they feature substantially different configurations (parameter sets) of ocean mixing and biogeochemical cycling. When projected into the future the similarity between the model responses breaks. Metrics such as changes in total oceanic carbon content and suboxic volume diverge between the model configurations as the Earth warms. Our results reiterate that advancing the understanding of oceanic mixing processes will reduce the uncertainty of future projections of oceanic biogeochemical cycles. Related to the latter, we suggest that an advanced understanding of oceanic biogeochemical cycles can be used for advancements in ocean circulation modules.
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Gardner, Carli. "Mash-up, Smash-up: Mixing Genres and Mediums to Rewrite History in Do Not Say We Have Nothing". Contemporary Kanata: Interdisciplinary Approaches To Canadian Studies, nr 1 (26.09.2021): 7–12. http://dx.doi.org/10.25071/2564-4661.17.
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In Madeleine Thien’s novel Do Not Say We Have Nothing, a historical photograph of three protestors at Tiananmen Square is directly inserted into the fictional text. The goal of my research is to start a scholarly conversation on this work by exploring the relationship between the historical image and the fictional text to establish Thien’s novel as postmodern. Drawing on postmodernist theories, this paper applies the works of prominent thinkers in the field to ask how the collision of genres and mediums (history and fiction; image and text), in Do Not Say We Have Nothing renders the novel postmodern. The first aim of this paper is to demonstrate the reciprocal relationship between text and image. The relationship is reciprocal because while the photograph certifies and undermines the story, the story also certifies and undermines the photograph. After establishing the multiple functions of the relationship between text and image, this paper explores how the collision of genres elicits multiple interpretations of the novel and the historical events it details. To understand how multiple interpretations of history destabilize historical metanarratives, this paper will finally investigate how the novel gives a voice to those omitted from history. By acknowledging Thien’s novel as postmodern, this paper analyzes the important role of fiction in representing those whose experiences are effaced by historical metanarratives. My postmodernist interpretation of Do Not Say We Have Nothing will provide new ways of reading and interpreting the novel and situating it within the canon of Canadian Literature.
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Brajon, Sophie, Jamie Ahloy-Dallaire, Nicolas Devillers i Frédéric Guay. "Social status and previous experience in the group as predictors of welfare of sows housed in large semi-static groups". PLOS ONE 16, nr 6 (8.06.2021): e0244704. http://dx.doi.org/10.1371/journal.pone.0244704.
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Mixing gestating sows implies hierarchy formation and has detrimental consequences on welfare. The effects of social stress on the most vulnerable individuals may be underestimated and it is therefore important to evaluate welfare between individuals within groups. This study aimed at investigating the impact of social status and previous experience in the group on well-being of sows housed in large semi-static groups. We assessed aggression (d0 (mixing), d2, d27, d29), body lesions (d1, d26, d84) and feeding order on 20 groups of 46–91 animals. Social status was based on the proportion of fights won during a 6-hr observation period between d0 and d2. Dominants (29%) were those who won more fights than they lost, Subdominants (25%) won fewer fights than they lost, Losers (23%) never won any fight in which they were involved while Avoiders (23%) were never involved in fights. Resident sows (70%) were already present in the group in the previous gestation while New sows (30%) were newly introduced at mixing. Subdominants and Dominants were highly involved in fights around mixing but this was more detrimental for Subdominants than Dominants, Losers and Avoiders since they had the highest body lesion scores at mixing. Avoiders received less non-reciprocal agonistic acts than Losers on d2 (P = 0.0001) and had the lowest body lesion scores after mixing. However, Avoiders and Losers were more at risk in the long-term since they had the highest body lesions scores at d26 and d84. They were followed by Subdominants and then Dominants. New sows fought more (P<0.0001), tended to be involved in longer fights (P = 0.075) around mixing and had more body lesions throughout gestation than Resident sows. Feeding order from one-month post-mixing was influenced both by the previous experience in the group and social status (P<0.0001). New sows, especially with a low social status, are more vulnerable throughout gestation and could serve as indicators of non-optimal conditions.
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Bazrgar, Masood, Hamid Gourabi, Anis Karimpour-Fard, Parnaz Borjian Boroujeni, Khadije Anisi, Bahar Movaghar i Mojtaba Rezazadeh Valojerdi. "Origins of Intraindividual Genetic Variation in Human Fetuses". Reproductive Sciences 26, nr 8 (19.11.2018): 1139–45. http://dx.doi.org/10.1177/1933719118808919.
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Background: Intraindividual copy number variation (CNV) origin is largely unknown. They might be due to aging and/or common genome instability at the preimplantation stage while contribution of preimplantation in human intraindividual CNVs occurrence is unknown. To address this question, we investigated mosaicism and its origin in the fetuses of natural conception. Methods: We studied normal fetuses following therapeutic abortion due to maternal indications. We analyzed the genome of 22 tissues of each fetus by array comparative genomic hybridization for intraindividual CNVs. Each tissue was studied in 2 microarray experiments; the reciprocal aberrations larger than 40 Kb, identified by comparing tissues of each fetus, were subsequently validated using quantitative polymerase chain reaction. Results: Through intraindividual comparison, frequency of reciprocal events varied from 2 to 9. According to the distribution pattern of the frequent CNV in derivatives of different germ layers, we found that its origin is early development including preimplantation, whereas CNVs with low frequency have occurred in later stages. Shared CNVs in both fetuses were belonged to thymus and related to the functional role of genes located in these CNVs. Conclusions: The origin of some of fetal CNVs is preimplantation stage. Each organ might inherit CNVs with an unpredictable pattern due to the extensive cell mixing/migration in embryonic development.
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Srihandayani, Luisa. "PERSPEKTIF YURIDIS DAN PRAKTIS PEMBEDAAN WANPRESTASI DAN PERBUATAN MELAWAN HUKUM". Jurnal Kawruh Abiyasa 1, nr 2 (8.01.2022): 166–81. http://dx.doi.org/10.59301/jka.v1i2.22.
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Reciprocal activity between 2 (two) parties is something that often happens in daily life. By carrying out these reciprocal activities, the parties have unknowingly entered into an agreement (legal act) that gives rise to an engagement (legal relationship in the field of property between 2 (two) or more people in which one party is entitled to something and the other party is obliged to do so. over something). The obligations agreed upon by the parties are often called 'achievements'. According to Article 1234 of the Civil Code (KUHPer), achievements born from an engagement can be in the form of: (1) giving something; (2) do something; (3) do nothing. In order for both parties to get what they want, the achievements in each engagement must be carried out by each party. Academically, defaults often intersect with 'acts against the law' (PMH) because both of them are related to acts of 'harming others' and the legal consequences of 'compensation'. In practice, there is often confusion where a default is said to be PMH, or vice versa. Whereas default and PMH are 2 (two) different legal acts. The phenomenon of mixing default and PMH can also be found in various judges' decisions in court.
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Capaldo, Anna. "The Adrenal Gland of Squamata (Reptilia): A Comparative Overview". Animals 13, nr 17 (22.08.2023): 2686. http://dx.doi.org/10.3390/ani13172686.
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The adrenal gland is a complex endocrine organ composed of two components: a steroidogenic tissue, which produces steroid hormones, and a chromaffin tissue, which mainly produces norepinephrine and epinephrine. Through evolution, their relationships with each other changed. They begin as isolated chromaffin and steroidogenic cell aggregates, typical of fish, and end with the advanced compact gland, typical of mammals, which consists of an external steroidogenic cortical zone and an internal chromaffin medullary zone. The adrenal gland of reptiles is unique because, with few exceptions, it is near the gonads and genital ducts, and the chromaffin and steroidogenic tissues are closely associated. However, the degree of mixing is variable. For example, in Squamata, the mixing degree of chromaffin and steroidogenic tissues, their reciprocal position in the gland, and the relative quantities of norepinephrine and epinephrine secreted by the chromaffin cells are extremely variable. This variability could be related to the phylogenetic history of the species. After a brief discussion of the adrenal gland and its main functions in vertebrates, this overview will examine the general characteristics of the adrenal gland of squamates, the differences in morphology of the gland, and the possible relationships with the phylogeny of the different species.
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Barajas, Belcy Karine Angarita, Rodolfo Cantet, Kaitlin E. Wurtz, Carly O’Malley, Janice Siegford, Catherine Ernst i Juan P. Steibel. "62 Improved estimation of indirect social genetic effects in group-housed pigs by quantifying behavioral interactions". Journal of Animal Science 97, Supplement_2 (lipiec 2019): 34. http://dx.doi.org/10.1093/jas/skz122.063.
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Abstract Traditional social genetic effects modeling assumes uniform intensity of interaction between group members. Tree breeders proposed relaxing this assumption by incorporating estimates of intensity of competition between pairs of individuals. Here, we incorporated the quantification of aggressive interactions between pairs of animals in the estimation of indirect social genetic effects on skin lesions in the anterior part of the body in growing pigs. The data consisted of 491 pigs (215 barrows and 276 gilts, mean of 66 ±5 days of age). Animals were housed in 37 pens (11 to 15 pigs by pen) over 7 replicates. Trained scorers counted the number of skin lesions immediately before and 24 hours after mixing pigs. Animals were video-recorded for 9 hours post mixing and trained observers quantified the type and duration of aggressive interactions between pairs of pigs. The number of skin lesions in the frontal part of the body 24 hours post-mixing was the response variable and the number of seconds that pairs of animals spent engaged in reciprocal fights was used to quantify the intensity of interaction. We compared three different models: A direct genetic additive model (DGE), a traditional social genetic effect model (TSGE) assuming uniform interactions, and an improved social genetic effect model (ISGE) that used intensity of interaction to parameterize social genetic effects. All models included fixed effects of sex, replicate, lesion scorer, initial weight and pre-mixing lesion count; a random effect of pen; and a random direct genetic effect. The model ISGE recovered the most variance (smallest σe2) and resulted in the highest estimated h2 (P < 0.005). The model TSGE produced estimates that did not differ significantly from DGE (P = 1). Contrarily, incorporating the intensity of interaction into the modeling of ISGE allowed direct and indirect genetic effects to be estimated separately, even in a small dataset.
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O’Malley, Carly I., Juan P. Steibel, Ronald O. Bates, Catherine W. Ernst i Janice M. Siegford. "The Social Life of Pigs: Changes in Affiliative and Agonistic Behaviors following Mixing". Animals 12, nr 2 (16.01.2022): 206. http://dx.doi.org/10.3390/ani12020206.
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This study investigated potentially affiliative behaviors in grow-finish pigs, how these behaviors changed over time and their relationship to agonistic behaviors. A total of 257 Yorkshire barrows were observed for agonistic (reciprocal fights, attacks) and affiliative (nosing, play, non-agonistic contact) behaviors after mixing (at 10 weeks of age), and weeks 3, 6, and 9 after mix. The least square means of affiliative behaviors were compared across time points. Relationships among affiliative and agonistic behaviors were assessed using generalized linear mixed models. Non-agonistic contact with conspecifics increased until week 6 then remained stable between weeks 6 and 9. Nosing was highest at mix, then decreased in the following weeks. Play was lowest at mix and highest at week 3. Affiliative behaviors were negatively related with aggression at mix (p < 0.001). Pigs who engaged in play and nosing behaviors were more likely to be involved in agonistic interactions in the weeks after mixing (p < 0.05), while pigs engaging in non-agonistic contact were less likely to be involved in agonistic interactions (p < 0.001). There appear to be relationships between affiliative and agonistic behaviors in pigs, with contact being the most predictive of less aggression. Future studies could focus on promoting positive non-agonistic contact in unfamiliar pigs as a way to mitigate aggressive interactions.
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Kijevcanin, Mirjana, A. B. Djordjevic, Ivona Grguric, Bojan Djordjevic i Slobodan Serbanovic. "Simultaneous correlation of the excess enthalpy and W-shaped excess heat capacity of 1, 4-dioxane- n-alkane systems by PRSV-HVOS CEOS". Journal of the Serbian Chemical Society 68, nr 1 (2003): 35–46. http://dx.doi.org/10.2298/jsc0301035k.
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In this work the Peng-Robinson-Stryjek-Vera (PRSV) equation of state coupled with the Huron-Vidal-Orbey-Sandler (HVOS) rule was tested for the correlation of the excess enthalpy (HE) and the excess heat capacity (cp E) alone and simultaneously. The HVOS mixing rule incorporates the NRTL equation as the GE model. All calculations were performed using the linear and reciprocal forms of the temperature dependent parameters of the models. For all the evaluations the 1,4-dioxane+n-alkane systems were chosen having in mind the unusually W-shaped concentration dependence of cp E for these systems. The correlation of the HE and cp E data alone for all the investigated systems using four coefficients and for the simultaneous correlation of HE+cp E data using six coefficients of the temperature dependent parameters of the PRSV-HVOS models could be considered as being very satisfactory.
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Hayashi, Makoto. "High-Cycle Thermal Fatigue Crack Initiation and Growth Behavior in a Semi-Infinite Plate Model". Journal of Pressure Vessel Technology 123, nr 3 (5.02.2001): 305–9. http://dx.doi.org/10.1115/1.1372327.
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At a T-junction in piping system, hot and cold water mixes in a whirl. The vibrating mixing boundary between the hot and cold water causes a temperature fluctuation on the inner surface of the pipe just after the connection point at the T-junction, and this temperature fluctuation yields a cyclic thermal stress near the pipe surface, resulting in crack initiation. In this study, the thermal stress distribution was analyzed for a semi-infinite plate model. The allowable water temperature range for the fatigue crack initiation was determined based on the mechanical fatigue test results. The thermal fatigue crack arrest behavior was analyzed based on the distributions of the stress intensity factor. The arrested crack depth is found to be in proportion to the reciprocal root of the frequency of the temperature fluctuation and is 3.8 mm for the frequency of 1 Hz.
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Cao, Mingshu, David A. Sleper, Fenggao Dong i Jiming Jiang. "Genomic in situ hybridization (GISH) reveals high chromosome pairing affinity between Lolium perenne and Festuca mairei". Genome 43, nr 2 (15.03.2000): 398–403. http://dx.doi.org/10.1139/g99-129.
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Intergeneric hybridizations have been made between species of Lolium and Festuca. It has been demonstrated, largely through conventional cytogenetic analysis, that the genomes of the two genera are related, however, much information is lacking on exactly how closely related the genomes are between the two species. We applied genomic in situ hybridization (GISH) techniques to the F1 hybrids of tetraploid Festuca mairei with a genomic constitution of M1M1M2M2 and diploid Lolium perenne with a genomic constitution of LL. It was shown in the triploid hybrids (LM1M2) that the chromosomes of M1 and M2 from F. mairei could pair with each other, and it was further discovered that L chromosomes of L. perenne paired with M1 and M2 chromosomes. Our results showed that meiocytes of Lolium-Festuca are amenable to GISH analysis, and provided direct evidence for the hypothesis that the chromosomes of Lolium and Festuca may be genetically equivalent and that reciprocal mixing of the genomes may be possible. Key words: Lolium, Festuca, in situ hybridization, meiosis.
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Marinelli, Lieta, Paolo Mongillo, Paolo Carnier, Stefano Schiavon i Luigi Gallo. "A Short Period of Darkness after Mixing of Growing Pigs Intended for PDO Hams Production Reduces Skin Lesions". Animals 10, nr 10 (23.09.2020): 1729. http://dx.doi.org/10.3390/ani10101729.
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Agonistic behavior after the regrouping of unfamiliar pigs has been recognized as one of the major welfare issues for pig husbandry, as it may result in lesions, lameness, and health problems. One scarcely investigated strategy to curb agonistic behavior is reducing the availability of visual stimuli potentially eliciting aggressions. In this study, we investigated the expression of agonistic behavior by growing pigs and the resulting accumulation of skin lesions over a period of 14 days following the formation of new social groups, which occurred in a condition of darkness maintained for 48 h. Compared to a simulated natural photoperiod (12 h light/day), darkness significantly reduced the number of skin lesions on the mid- and rear thirds of pigs’ body (p ≤ 0.01). A lack of corresponding decrease in frequency and duration of agonistic interactions suggests that darkness acts by decreasing the efficacy, not the expression, of aggressions. Furthermore, the location of lesions mostly affected by darkness indicates that the latter mostly acted by reducing the possibility of pigs to convey damage to a fleeing conspecific, rather than to one involved in a reciprocal fighting. The lighting regime provided did not affect growth performance traits of a 17-weeks feeding trial. The present results identify in the provision of darkness an easily applicable, and relatively inexpensive intervention, that leads to the reduction of skin lesions.
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Strocchi, A., G. Corazza, J. Furne, C. Fine, A. Di Sario, G. Gasbarrini i M. D. Levitt. "Measurements of the jejunal unstirred layer in normal subjects and patients with celiac disease". American Journal of Physiology-Gastrointestinal and Liver Physiology 270, nr 3 (1.03.1996): G487—G491. http://dx.doi.org/10.1152/ajpgi.1996.270.3.g487.
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Normal intestinal absorption of nutrients requires efficient luminal mixing to deliver solute to the brush border. Lacking such mixing, the buildup of thick unstirred layers over the mucosa markedly retards absorption of rapidly transported compounds. Using a technique based on the kinetics of maltose hydrolysis, we measured the unstirred layer thickness of the jejunum of normal subjects and patients with celiac disease, as well as that of the normal rat. The jejunum of humans and rats was perfused with varying maltose concentrations, and the apparent Michaelis constant (Km) and maximal velocity (Vmax) of maltose hydrolysis were determined from double-reciprocal plots. The true Km of intestinal maltase was determined on mucosal biopsies. Unstirred layer thickness was calculated from the in vivo Vmax and apparent Km and the in vitro Km of maltase. The average unstirred layer thickness of 11 celiac patients (170 micron) was seven times greater than that of 3 controls (25 micron). The unstirred layer of each celiac exceeded that of the controls. A variety of factors could account for the less efficient luminal stirring observed in celiacs. Although speculative, villous contractility could be an important stirring mechanism that would be absent in celiacs with villous atrophy. This speculation was supported by the finding of a relatively thick unstirred layer (mean: 106 micron) in rats, an animal that lacks villous contractility. Because any increase in unstirred layer slows transport of rapidly absorbed compounds, poor stirring appears to represent a previously unrecognized defect that could contribute to malabsorption in celiac disease and, perhaps, in other intestinal disorders.
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Rault, Jean-Loup. "Social interaction patterns according to stocking density and time post-mixing in group-housed gestating sows". Animal Production Science 57, nr 5 (2017): 896. http://dx.doi.org/10.1071/an15415.
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Housing systems should enable animals to interact socially while minimising aggression. This study investigated whether social interaction patterns in groups of indoor-housed gestating sows are affected by stocking density (‘SD’), by varying the number of sows per pen, and day after mixing. Unacquainted sows were grouped within 5 days of insemination at 1.45 (High; ‘H-SD’), 2.0 (Moderate; ‘M-SD’) or 2.9 m2 per sow (Low; ‘L-SD’) by placing 20, 14 or 10 sows per pen. Five pens per treatment were represented, and within each pen, 10 focal sows were observed. Social behaviours between focal sows were analysed continuously for 15 min after drop-feeding the day after mixing (Day 2) and 1 week later (Day 9), and plasma cortisol and progesterone concentrations analysed on Days 2 and 26. Overall, 587 interactions were observed, with 59% being short one reciprocal actions. Sows used more physical aggression at H-SD on Day 2 such as bites (vs M-SD and L-SD: both P < 0.01), head knocks and pushes (vs L-SD: P = 0.01; vs M-SD: P = 0.06), whereas social interactions at lower SD were more frequent (L-SD vs H-SD: P = 0.004; L-SD vs M-SD: P = 0.02) and contained presumably neutral social behaviours such as nose contacts (L-SD vs H-SD: P = 0.06; M-SD vs H-SD: P = 0.07), or non-physical agonistic behaviours such as threats (L-SD vs H-SD: P = 0.07). A first-order Markov transitional analysis revealed positive feedback loops for bites and knocks or pushes at higher SD on Day 2 (all P < 0.05). Cortisol concentration decreased as SD decreased (L-SD vs H-SD: P < 0.001; L-SD vs M-SD: P = 0.02; M-SD vs H-SD: P = 0.07). Hence, interactions were more aggressive and less frequent at higher SD at Day 2 post-mixing, but differences vanished at Day 9. Valuable information can be gained from analysing the type of social behaviours and behavioural sequences, in addition to overall aggression frequency.
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Blangy, J. P., S. Strandenes, D. Moos i A. Nur. "Ultrasonic velocities in sands—revisited". GEOPHYSICS 58, nr 3 (marzec 1993): 344–56. http://dx.doi.org/10.1190/1.1443418.
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Ultrasonic compressional and shear‐wave velocities of isotropic sands are shown to be dependent on their mineralogy, their porosity, their fluid content, and their state of consolidation, under fixed temperature and pressure conditions. This leads to a distinction between two broad classes of sands: those that are well consolidated, and those that are loosely consolidated. Changes in elastic velocities reflect changes in the ratio of bulk and shear moduli to density in response to lithologic variations. We decouple the two effects by examining changes in elastic moduli with respect to changes in lithology, and we observe three main points: (1) For consolidated sandstones, the effects of mineralogy and porosity can be approximated both empirically and theoretically by a modified isostrain theory: the dry bulk and shear moduli of the rock aggregate follow a “mixing law,” being linear combinations of the respective moduli of the individual constituents. The dry elastic moduli of families of clean sands and shaley sands are linear functions of porosity, with decreasing y‐axis intercepts as their clay‐to‐sand ratio increases. (2) Loosely consolidated sands and sandy shales appear to follow a behavior closer to that of the isostress theory for suspensions: the reciprocals of the bulk and shear moduli of the rock aggregate are linear combinations of the reciprocal moduli of their individual constituents. In general, the elastic moduli of poorly lithified sands are less sensitive to changes in mineralogy and porosity than those of consolidated sandstones. (3) For high permeability sands like the loosely consolidated sands of Troll, the Biot‐Gassman theory is a good approximation to the effects of fluids on seismic velocities. With our understanding of elastic moduli, we then show that dry ratios [Formula: see text] increase with porosity and clay content.
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Vallianatos, M., S. C. Lougheed i P. T. Boag. "Phylogeography and genetic characteristics of a putative secondary-contact zone of the loggerhead shrike in central and eastern North America". Canadian Journal of Zoology 79, nr 12 (1.12.2001): 2221–27. http://dx.doi.org/10.1139/z01-157.
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The loggerhead shrike (Lanius ludovicianus) is found throughout North America in grassland and open scrub habitats. We previously described four loggerhead shrike management units found in central and eastern North America within the geographic ranges of three subspecies, L. l. migrans, L. l. ludovicianus, and L. l. excubitorides. A contact zone has been suggested to occur between L. l. migrans and L. l. excubitorides. The present study uses mitochondrial DNA sequence data to explore historical, ecological, and geographical factors that may have played a role in the genetic differentiation of these four management units, and examines the evidence for and characteristics of the migransexcubitorides contact zone. Geographically discrete, monophyletic clades were not evident, but the distribution of haplotypes (especially those exceeding 10% overall frequency) indicated some phylogeographic structure that perhaps reflects an intermediate stage of differentiation between paraphyly and reciprocal monophyly. The contact zone between L. l. migrans and L. l. excubitorides is supported by the mixing of haplotypes unique to each of the hybridizing populations and intermediate frequencies of common haplotypes. We interpret these patterns as possibly reflecting the impact of both glacial refugial dynamics and anthropogenic changes to habitat in eastern North America.
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Delmotte, Isabelle. "Environmental silence and its renditions in a movie soundtrack". Swamphen: a Journal of Cultural Ecology (ASLEC-ANZ) 1 (24.10.2011): 58–67. http://dx.doi.org/10.60162/swamphen.1.10588.
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Audio technology and contemporary sonic environments have affected perceptual habits at both individual and communal levels. As the perception of sound fluctuates between modes of attention and inattention, the narrative expectations generated by sonic materials may follow patterns of individual physical response that would in turn modify some communal perceptions of environmental soundscapes, silences in particular. In current sound design practice and the mainstream movie industry, the use of absolute silence as an absence of sound seems almost irrelevant. Film silence has become the complex technical product of mixing sounds, a view that departs from silence as a broad sound element added to vocal enunciation, music and special sound effects. As a subtle component of a narrative, cinematic silence may be at the junction of representation and reproduction of the acoustic biomass that we create and communicate to others. This paper examines how the subjective enaction of audio-filmic silence could develop from evolving acoustic ecologies, corporeal integration and cultural convention. In such a context, film silence could be a reciprocal tool that may generate modes of expression used to assess our personal and communal notions of environmental silences.
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RAGOT, BRIGITTE R. "Nonlinear particle dynamics in a broadband turbulence wave spectrum". Journal of Plasma Physics 60, nr 2 (wrzesień 1998): 299–329. http://dx.doi.org/10.1017/s0022377898006795.
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In the statistical quasilinear theory of weak plasma turbulence, charged particles moving in electrostatic fluctuations diffuse in velocity, i.e. the velocity variance 〈Δv2(t)〉 increases linearly with time t, for times long compared with the auto-correlation time τac of the field, which may be estimated as the reciprocal of the spectral width of the fluctuations. Recent test-particle simulations have revealed a new regime at very long timescales t[Gt ]τac where quasilinear theory breaks down, for intermediate field amplitudes. As this behaviour is not consistent with a diffusion on quasilinear timescales, the problem of the motion of particles in a broadband wave field, for the case of a slowly growing field, is considered here from a purely dynamical point of view, introducing no statistics on the field and no restriction on the amplitude of this field. By determining, on a given timescale, and in the frame of wave–particle interaction, the spectral width over which waves interact efficiently with a particle, a new timescale is found: the nonlinear time of wave–particle interaction τNL∝ (spectral density of energy)−1/3[Gt ]τac. This is the correlation time of the dynamics. For times shorter than τNL, the particles trajectories remain globally regular, and do not separate: they follow a quasifractal set of dimension 2. For times long compared with τNL, there appears a ‘true’ diffusive regime with mixing and decorrelation, due to nonlinear mixing in phase space and the localization of the wave–particle interaction. These theoretical results are confirmed by a numerical study of the velocity variance as a function of time. In particular, the particle dynamics really do become diffusive on timescales several orders of magnitude longer than that predicted by quasilinear theory (namely [Gt ]τNL[Gt ]τac). Finally, deviations from the quasilinear value of the diffusion coefficient and wave growth rate, discussed in the literature, are explained.
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Sommariva, Roberto, Louisa J. Kramer, Leigh R. Crilley, Mohammed S. Alam i William J. Bloss. "An instrument for in situ measurement of total ozone reactivity". Atmospheric Measurement Techniques 13, nr 3 (2.04.2020): 1655–70. http://dx.doi.org/10.5194/amt-13-1655-2020.
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Abstract. We present an instrument for the measurement of total ozone reactivity – the reciprocal of the chemical lifetime of ozone (O3) – in the troposphere. The Total Ozone Reactivity System (TORS) was developed with the objective to study the role of biogenic volatile organic compounds (BVOCs) as chemical sinks of tropospheric ozone. The instrument was extensively characterized and tested in the laboratory using individual BVOCs and small plants (lemon thyme, Thymus citriodorus) in a Teflon bag and proved able to measure reactivities corresponding to >4.5×10-5 s−1 (at 5 min averaging time), with an estimated total uncertainty of ∼32%. Such reactivities correspond to >20 ppb of α-pinene or >150 ppb of isoprene in isolation – larger than typical ambient levels but observable in environmental chamber and enclosure experiments as well as in BVOC-rich environments. The functionality of TORS was demonstrated in quasi-ambient conditions with a deployment in a horticultural glasshouse containing a range of aromatic plants. The measurements of total ozone reactivity made in the glasshouse showed a clear diurnal pattern, following the emissions of BVOCs, and are consistent with mixing ratios of tens of parts per billion of monoterpenes and several parts per billion of sesquiterpenes.
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Sari, Rika Ratna, Danaë M. A. Rozendaal, Danny Dwi Saputra, Kurniatun Hairiah, James M. Roshetko i Meine van Noordwijk. "Balancing litterfall and decomposition in cacao agroforestry systems". Plant and Soil 473, nr 1-2 (8.01.2022): 251–71. http://dx.doi.org/10.1007/s11104-021-05279-z.
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Abstract Backgrounds and aims Litter protects the underlying soil, depending on litterfall and decomposition, but dynamics of the standing litter stock in agroforestry systems remain poorly understood. We aimed to unravel effects of litter quality, temporal patterns, microclimate, and a possible home-field advantage (HFA) on standing litter dynamics across a land-use gradient. Methods We quantified litterfall, the standing litter stock, and microclimate during a year in (remnant) forest, cacao-based simple and complex agroforestry, cacao monocultures, and annual crops in a cacao producing area in Indonesia. We conducted a reciprocal litter transfer experiment, and tested decomposition rates of pruning residues. Standing litter stocks during the year were estimated from monthly litterfall and decomposition rates. Results Variation in litter quality influenced decomposition rates more strongly than variation in microclimate or HFA. Lower litter quality in complex agroforestry and in the cacao monoculture decreased the decay rate compared to simple agroforestry systems; mean litter residence time was over a year. Mixing high- and low-quality material in pruning residues modified the decomposition rate, soil C and N changes, offering options for targeted management of soil protection and nutrient release. Conclusions The seasonal patterns of litterfall and relatively slow decomposition rates supported permanence of the litter layer in all cacao production systems, protecting the underlying soil.
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Falk, K. C., G. F. W. Rakow i R. K. Downey. "The utilization of heterosis for seed yield in hybrid and synthetic cultivars of summer turnip rape". Canadian Journal of Plant Science 78, nr 3 (1.07.1998): 383–87. http://dx.doi.org/10.4141/p97-076.
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Hybrids of summer turnip rape (Brassica rapa L. syn. B. campestris L.) have been shown to exhibit high levels of heterosis. This study was undertaken to determine whether the heterosis for seed yield observed in hybrids could be captured by synthetic cultivars of turnip rape. The agronomic performance of reciprocal inter-cultivar hybrids and their corresponding two-component synthetics was studied using four turnip rape cultivars. Hybrid seed was produced by hand pollination in the greenhouse and Syn1 seed was produced by mixing equal proportions of each parent to form the base seed (Syn0) of each synthetic, and planting these in isolation in the field. The seed yield of hybrids, synthetics and parents were similar in 1985 while in 1986, hybrids yielded 25% and synthetics 23% more than parents. Actual versus predicted synthetic yields were similar except for one synthetic, Echo-Torch in 1986, where the actual yield exceeded the predicted value. Hybrid yields may have been underestimated by the chosen prediction method and therefore the yield potential of hybrids would be greater than for synthetics in turnip rape. However, until a suitable pollination control system is developed in this species, synthetic cultivars are a viable alternative to hybrids. Key words: Turnip rape (summer), synthetic, hybrids, Brassica rapa, B. campestris
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Matassa, Roberto, Silvia Orlanducci, Emanuela Tamburri, Valeria Guglielmotti, Daniela Sordi, Maria Letizia Terranova, Daniele Passeri i Marco Rossi. "Characterization of carbon structures produced by graphene self-assembly". Journal of Applied Crystallography 47, nr 1 (8.01.2014): 222–27. http://dx.doi.org/10.1107/s1600576713029488.
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Low-dimensional carbon-based materials, in particular two-dimensional graphenic carbon structures, have been produced from single-walled carbon nanotube disruption using high-shear mixing and/or treatments in sulfonitric acid mixtures at both room and high temperature. Among other two-dimensional graphenic carbon structures, colloidal dispersions of graphenic nanoflakes have been obtained. Different structural arrangements, resulting from the reorganization of carbon because of the disruption procedures applied, were observed through selected area electron diffraction (SAED) and through reflection high-energy electron diffraction (RHEED) analyses coupled to transmission and scanning electron microscopy observations. Such combined investigations in the real and reciprocal space provided structural information at the nanoscale on the clustering of graphene layers in nanoplatelets or/and on their assembly into highly ordered (single-crystal) nanosheets. Furthermore, a different carbon phase exhibiting an orthorhombic cell withCmmasymmetry has been detected by SAED and RHEED analyses. In addition, a variety of self-assemblies of hexagonal basal planes have been observed to occur as the result of their different rotational and/or translational stacking faults. Overall, the reported results contribute to define the conditions for a controlled self-assembly of graphene-based structures with tailored dimensions, which is an important technological challenge, as their structure at the nanoscale dramatically affects their electrical properties.
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MELVILLE, W. KENDALL, ROBERT SHEAR i FABRICE VERON. "Laboratory measurements of the generation and evolution of Langmuir circulations". Journal of Fluid Mechanics 364 (10.06.1998): 31–58. http://dx.doi.org/10.1017/s0022112098001098.
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We present laboratory measurements of the generation and evolution of Langmuir circulations as an instability of a wind-driven surface shear layer. The shear layer, which is generated by an accelerating wind starting from rest above a quiescent water surface, both accelerates and deepens monotonically until the inception of the Langmuir circulations. The Langmuir circulations closely follow the initial growth of the wind waves and rapidly lead to vertical mixing of the horizontal momentum and a deceleration of the surface layer. Prior to the appearance of the Langmuir circulations, the depth of the shear layer scales with (vt)1/2 (v is the kinematic viscosity and t is time), in accordance with molecular rather than turbulent transport. For final wind speeds in the range 3 to 5 m s−1, the wavenumber of the most unstable Langmuir circulation normalized by the surface wavenumber, k*lc, is 0.68±0.24, at a reciprocal Langmuir number, La−1, of 52±21. The observations are compared with available theoretical results, although none are directly applicable to the conditions of the experiments. The implications of this work for the generation and evolution of Langmuir circulations in the ocean and other natural water bodies are discussed.
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Zhang, Xiu-Qin, Nobuyuki Takakura, Yuichi Oike, Tomohisa Inada, Nicholas W. Gale, George D. Yancopoulos i Toshio Suda. "Stromal cells expressing ephrin-B2 promote the growth and sprouting of ephrin-B2+ endothelial cells". Blood 98, nr 4 (15.08.2001): 1028–37. http://dx.doi.org/10.1182/blood.v98.4.1028.
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Ephrin-B2 is a transmembrane ligand that is specifically expressed on arterial endothelial cells (ECs) and surrounding cells and interacts with multiple EphB class receptors. Conversely, EphB4, a specific receptor for ephrin-B2, is expressed on venous ECs, and both ephrin-B2 and EphB4 play essential roles in vascular development. The bidirectional signals between EphB4 and ephrin-B2 are thought to be specific for the interaction between arteries and veins and to regulate cell mixing and the making of particular boundaries. However, the molecular mechanism during vasculogenesis and angiogenesis remains unclear. Manipulative functional studies were performed on these proteins in an endothelial cell system. Using in vitro stromal cells (OP9 cells) and a paraaortic splanchnopleura (P-Sp) coculture system, these studies found that the stromal cells expressing ephrin-B2 promoted vascular network formation and ephrin-B2+ EC proliferation and that they also induced the recruitment and proliferation of α-smooth muscle actin (α-SMA)–positive cells. Stromal cells expressing EphB4 inhibited vascular network formation, ephrin-B2+ EC proliferation, and α-SMA+ cell recruitment and proliferation. Thus, these data suggest that ephrin-B2 and EphB4 mediate reciprocal interactions between arterial and venous ECs and surrounding cells to form each characteristic vessel.
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Fialko, N. М., Ju V. Sherenkovskyi, N. O. Meranova, S. A. Alioshko i K. V. Rokytko. "PECULIARITIES OF FLOW AND MIXTURE FORMATION IN MICROIET BURNER DEVICES WITH ASYMMETRIC FUEL DISTRIBUTION". Thermophysics and Thermal Power Engineering 41, nr 1 (4.03.2019): 11–19. http://dx.doi.org/10.31472/ttpe.1.2019.2.
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The purpose of the work is to establish the regularities of the isothermal flow and the mixture formation of the fuel gas and oxidant in the microjet burner devices with an asymmetric fuel supply. The main tasks of the work are the analysis of the effects of the influence of the value of excess air factor on the flow structure and the features of the mixing of fuel and oxidant. As a method of research, the CFD modeling method using the FLUENT code was used. According to the results of the studies carried out in the relatively wide limits of the change in the excess air factor (1.5 ≤ α ≤ 4.0), the regularities of the effect of the value of this factor on such flow characteristics in the burners studied as the length of the reverse current zone behind the flame stabilizer, which is responsible for the combustion stability, the location of main vortex in this zone, the values of the mean-square velocity pulsations, and so on. The features of the mixture formation in the variation of the α value in the burner devices under investigation are revealed. The dependence on the mean α of the methane concentration in the reciprocal zone is established and given its interpretation, taking into account a number of competing factors.
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Addabbo, Tommaso, Ada Fort, Elia Landi, Riccardo Moretti, Marco Mugnaini i Valerio Vignoli. "Strategies for the Accurate Measurement of the Resonance Frequency in QCM-D Systems via Low-Cost Digital Techniques". Sensors 22, nr 15 (31.07.2022): 5728. http://dx.doi.org/10.3390/s22155728.
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In this paper, an FPGA (Field Programmable Gate Array)-based digital architecture for the measurement of quartz crystal microbalance (QCM) oscillating frequency of transient responses, i.e., in QCM-D (QCM and Dissipation) applications, is presented. The measurement system is conceived for operations in liquid, with short QCM transient responses due to the large mechanical load. The proposed solution allows for avoiding the complex processing systems typically required by the QCM-D techniques and grants frequency resolutions better than 1 ppm. The core of the architecture is a reciprocal digital frequency meter, combined with the preprocessing of the QCM signal through mixing operations, such as a step-down of the input frequency and reducing the measurement error. The measurement error is further reduced through averaging. Different strategies are proposed to implement the proposed measurement solution, comprising an all-digital circuit and mixed analog/digital ones. The performance of the proposed architectures is theoretically derived, compared, and analyzed by means of experimental data obtained considering 10 MHz QCMs and 200 μs long transient responses. A frequency resolution of about 240 ppb, which corresponds to a Sauerbrey mass resolution of 8 ng/cm2, is obtained for the all-digital solution, whereas for the mixed solution the resolution halves to 120 ppb, with a measurement time of about one second over 100 repetitions.
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Orlova, Natalia B., i Mikhail I. Kurkin. "Peierles transition in a linear chain of exchange related spins". Proceedings of the Russian higher school Academy of sciences, nr 4 (27.12.2021): 7–14. http://dx.doi.org/10.17212/1727-2769-2021-4-7-14.
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The loss of stability of the antiferromagnetic state of matter respective to the Peierls transition is calculated in the framework of a new model of magnetic sublattices. In this new model, in contrast to the Anderson-Ziman sublattice model, the antiferromagnetic spin ordering is provided by a weak influence of magnetic anisotropy. Magnetic anisotropy suppresses exchange mixing with a sufficiently large number of spins in the sublattice . The Peierls transition consists in the deformation in a linear chain of atoms, namely the convergence of neighboring atoms, at which the period of the crystal lattice increases by factor of two. When atoms approach, exchange interaction is established between a pair of nearest atomic spins only. Based on the new model of magnetic sublattices, the antiferromagnetic sublattice state of the periodic chain of spins is found to be unstable respective to the transition to the Peierls state. During the transition to the "spin-Peierls" state, the spins of neighboring atoms will be ordered antiparallelly, but since there is no preferred direction of spin ordering, it is impossible to introduce the concept of magnetic sublattices. Such magnetic states can be suggested from the exponential dependence of the magnetic susceptibility on the reciprocal temperature. The electrons magnetism in this state is determined by the atomic diamagnetism if the frequencies of thermal motion are small compared to the exchange frequency.
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Miftahof, R., i N. Akhmadeev. "Numerical Simulations of Effects of Multiple Neurotransmission on Intestinal Propulsion of a Non-Deformable Bolus". Computational and Mathematical Methods in Medicine 8, nr 1 (2007): 11–36. http://dx.doi.org/10.1080/10273660701248650.
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Electrophysiological mechanisms of co-transmission by serotonin (5-HT) and acetylcholine (ACh), co-expression of receptor types 5-HT type 3 and 4, nicotinic cholinerginc (nACh) and muscarinic cholinergic (μACh), and effects of selective and non-selective 5-HT3and 5-HT4receptor agonists/antagonists, on intestinal propulsion of a solid non-deformable bolus were studied numerically. Results indicated that the propagation of the wave of excitation in the presence of 5-HT3receptor antagonists was supported by co-release of ACh. Co-stimulation of 5-HT3, nACh and μACh receptors significantly impairs propulsive activity of the gut. In an ACh-free environment,Lotronexincreased the transit time of the bolus along a segment of the gut. In the presence of ACh,Lotronexproduced intensive tonic-type contractions in the longitudinal and circular smooth muscle layers and eliminated propulsive activity.Zelnormpreserved the reciprocal electromechanical relationships between the longitudinal and circular smooth muscle layers. The drug changed the normal mixing pattern of activity to an expulsive type. Treatment of the gut with selective 5HT4receptor antagonists increased the transit time by disrupting the migrating myoelectrical complex.Cisaprideincreased the excitability of the myenteric nervous plexus and increased the frequency of slow waves. In the presence ofCisapridesmooth muscle syncytia responded with the generation of tonic contractions, resulting in a “squeezing” type of bolus movement. Comparison of the theoretical results toin vivoandin vitroexperimental data indicated satisfactory qualitative and quantitative agreement.
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Günther-Ausborn, Susanne, Pieter Schoen, Ingrid Bartoldus, Jan Wilschut i Toon Stegmann. "Role of Hemagglutinin Surface Density in the Initial Stages of Influenza Virus Fusion: Lack of Evidence for Cooperativity". Journal of Virology 74, nr 6 (15.03.2000): 2714–20. http://dx.doi.org/10.1128/jvi.74.6.2714-2720.2000.
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ABSTRACT Membrane fusion mediated by influenza virus hemagglutinin (HA) is believed to proceed via the cooperative action of multiple HA trimers. To determine the minimal number of HA trimers required to trigger fusion, and to assess the importance of cooperativity between these HA trimers, we have generated virosomes containing coreconstituted HAs derived from two strains of virus with different pH dependencies for fusion, X-47 (optimal fusion at pH 5.1; threshold at pH 5.6) and A/Shangdong (optimal fusion at pH 5.6; threshold at pH 6.0), and measured fusion of these virosomes with erythrocyte ghosts by a fluorescence lipid mixing assay. Virosomes with different X-47-to-A/Shangdong HA ratios, at a constant HA-to-lipid ratio, showed comparable ghost-binding activities, and the low-pH-induced conformational change of A/Shangdong HA did not affect the fusion activity of X-47 HA. The initial rate of fusion of these virosomes at pH 5.7 increased directly proportional to the surface density of A/Shangdong HA, and a single A/Shangdong trimer per virosome appeared to suffice to induce fusion. The reciprocal of the lag time before the onset of fusion was directly proportional to the surface density of fusion-competent HA. These results support the notion that there is no cooperativity between HA trimers during influenza virus fusion.
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Zhou, Aiwu, James A. Huntington i Robin W. Carrell. "Formation of the Antithrombin Heterodimer In Vivo and the Onset of Thrombosis". Blood 94, nr 10 (15.11.1999): 3388–96. http://dx.doi.org/10.1182/blood.v94.10.3388.422k20_3388_3396.
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Antithrombin is shown to undergo a slow spontaneous conversion to its inactive latent conformation with readily discernible amounts present in plasma on incubation at 37°C for 72 hours. More rapid conversion occurs on incubation of isolated antithrombin at 41°C or 50°C, but the appearance on electrophoresis of free latent antithrombin is preceded by the formation, in reciprocal proportions, of a new slow band. This slow component is shown to be a heterodimer of active and latent antithrombin. It can be isolated as a single stable band either by incubation of antithrombin or by mixing equimolar proportions of active and latent antithrombin under the same conditions that give overnight crystallization of the active/latent antithrombin heterodimer. Similarly, equimolar addition of latent antithrombin to plasma results electrophoretically in a quantitative shift to the slower heterodimer mobility. Clinically, the presence of latent antithrombin is potentially deleterious, because its linkage to form the heterodimer results in inactivation of the otherwise normal molecule linked to the latent antithrombin. In the case of -antithrombin, because the dimer readily dissociates, there is only a 11% additive loss of activity, but with β-antithrombin the dimer appears more stable, with the additive loss of activity from the normal β component being 21%, increasing to 33% on stabilization of the dimer with heparin. This linked and selective loss of activity of β-antithrombin provides an explanation for the unexpected severity of thrombotic episodes in heterozygotes with conformationally unstable antithrombins.
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AZAIEZ, J. "Linear stability of free shear flows of fibre suspensions". Journal of Fluid Mechanics 404 (10.02.2000): 179–209. http://dx.doi.org/10.1017/s002211209900717x.
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A linear stability analysis of the mixing layer in the presence of fibre additives is presented. Using a formulation based on moments of the probability distribution function to determine the particle orientation, we extend the classical linear stability theory and derive a modified Orr–Sommerfeld equation. It is found that, for large Reynolds numbers, the flow instability is governed by two parameters: a dimensionless group H, analogous to a reciprocal Reynolds number representing the importance of inertial forces versus viscous forces associated with the anisotropic elongational viscosity of the suspension; and a coefficient CI that accounts for inter-particle hydrodynamic interactions. A parametric study reveals that both parameters can induce an important attenuation of the flow instability. Furthermore, we show that the stabilizing effects arise from the orientation diffusion due to hydrodynamic interactions, and not from the anisotropy induced by the presence of fibres in the flow, as speculated before. The examination of profile contours of different perturbation terms and the analysis of the rate of production of enstrophy show clearly that the main factor behind the reduction of the flow instability is associated with the fibre shear stress disturbance. This disturbance acts as a dissipative term as the fibres, due to the orientational diffusivity arising from hydrodynamic interactions, deviate from the fully aligned anisotropic orientation. On the other hand, fibre normal stresses act as a destabilizing factor and are important only in the absence of hydrodynamic interactions.
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Shapiro, Alan. "Drag-Induced Transfer of Horizontal Momentum between Air and Raindrops". Journal of the Atmospheric Sciences 62, nr 7 (1.07.2005): 2205–19. http://dx.doi.org/10.1175/jas3460.1.
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Abstract A theoretical model for unsteady drag-induced transfer of horizontal momentum between air and raindrops in moderate to heavy rainfall is presented. The model accounts for a two-way coupling in which the relative horizontal motion between air and raindrops appears as a drag forcing in both the air and raindrop equations of motion. Analytical solutions of these coupled equations are obtained for the case of rain falling through (i) an initial step change in environmental wind, (ii) a uniform shear profile, and (iii) periodically varying vertical shears of various wavenumbers (a crude proxy for turbulent eddies). Formulas for the propagation (descent) speeds of the shear zones are obtained for (ii), (iii), and for the later stage of (i). However, these speeds are generally quite small—on the order of a few centimeters per second even for heavy rainfall. More importantly, the solutions of (i) and (iii) indicate that the drag interaction leads to a decay of the velocity gradients. A formula for the e-folding decay time of the periodically varying shear profiles indicates that at small wavelengths, the smallest decay times are found for the smaller drops, but at large wavelengths, the smallest decay times are found for the larger drops. The decay times decrease with decreasing wavelength, and approach a value equal to the reciprocal of the product of the rainwater mixing ratio and a drag parameter in the limit of vanishing wavelength. For parameters typical of moderate to heavy rainfall, the small-scale decay times are on the order of a few minutes.
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van Oudheusden, B. W. "An experimental study of transition and the development of turbulence in a linearly retarded boundary-layer flow". Aeronautical Journal 103, nr 1029 (listopad 1999): 497–510. http://dx.doi.org/10.1017/s0001924000064253.
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AbstractAn experimental investigation was carried out of the incompressible boundary layer flow along a flat plate, in the presence of an adverse pressure gradient that corresponds to a linear retardation of the free stream velocity. The turbulence level in the free-stream was 0·12% and transition occurred with the laminar boundary layer being close to separation. For three values of the Reynolds number (2·56, 3·11 and 4·09 million based on the reference length that is defined as the reciprocal of the nondimensional-velocity gradient) the laminar, transitional and turbulent regions were studied by single (normal) hot-wire surveys at several streamwise positions. This allows the fluctuations of the streamwise velocity component to be followed from the amplification of laminar instability waves, through breakdown in the intermittency region, and the subsequent development towards a more or less developed turbulence structure. The study reveals that within the transition region fluctuation levels are reached throughout a large part of the boundary layer that are significantly higher than those in fully developed turbulent flow, which is partly a direct consequence of the intermittent character of the flow. For the highest Reynolds number additional cross-wire surveys were carried out in the turbulent region to observe the development of the turbulent stresses following transition. The data are interpreted in terms of structural coefficients, eddy viscosity and mixing length. Also, these results indicate that the transition process can be associated with turbulence levels well in excess of those occurring in fully developed turbulence, and reveal the relaxation of the outer region turbulence structure.
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Werner, Winter Jade. "All in the Family? Missionaries, Marriage, and Universal Kinship in Jane Eyre". Nineteenth-Century Literature 72, nr 4 (1.03.2018): 452–86. http://dx.doi.org/10.1525/ncl.2018.72.4.452.
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Winter Jade Werner, “All in the Family? Missionaries, Marriage, and Universal Kinship in Jane Eyre” (pp. 452–486) As a number of critics have shown, Charlotte Brontë’s Jane Eyre (1847) has as a central theme the analysis of certain essential contradictions in a constellation of ideas concerning kinship and race. In this essay, I propose that these contradictions—which receive fullest exposition in the missionary St John’s determination to wed his kinswoman Jane—gesture toward the history of these issues as they were enacted in missionary literature. Jane Eyre, this essay contends, roots itself in a fraught phase of the Protestant missionary movement: the brief period of time prior to the 1820s when missionary societies, eager to realize what they termed “universal kinship,” not only permitted but encouraged missionaries to enter into interracial marriages. These marriages, however, proved more reciprocal in influence than missionary societies had anticipated. Ultimately they undermined assumptions of British Christians’ “natural” superiority over “natives”—the very assumptions that underwrote missionary work in the first place. Unnerved by the reciprocity and openness these unions appeared to establish between spouses, missionary societies began discouraging intermarriage and dissociated conceptions of “universal kinship” from actual racial mixing. This period of controversy unifies the novel’s anxious focus on family formation and interracial marriage. In exposing how intermarriages worked to legitimate and problematize evangelical understandings of universal kinship, Jane Eyre ultimately suggests that there exists a crucial link between St John’s proposed endogamous union with his kinswoman and Rochester and Bertha’s intermarriage—the former becomes the conceptual alternative to the latter.
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Ohuchi, Masanobu, Reiko Ohuchi, Tatsuya Sakai i Akira Matsumoto. "Tight Binding of Influenza Virus Hemagglutinin to Its Receptor Interferes with Fusion Pore Dilation". Journal of Virology 76, nr 24 (15.12.2002): 12405–13. http://dx.doi.org/10.1128/jvi.76.24.12405-12413.2002.
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ABSTRACT Deletion of oligosaccharide side chains near the receptor binding site of influenza virus A/USSR/90/77 (H1N1) hemagglutinin (HA) enhanced the binding of HA to erythrocyte receptors, as was also observed with A/FPV/Rostock/34 (H7N1). Correlated with the enhancement of binding activity, the cell fusion activity of HA was reduced. A mutant HA in which three oligosaccharide side chains were deleted showed the highest level of binding and the lowest level of fusion among the HAs tested. The cell fusion activity of the oligosaccharide deletion mutant of HA, however, was drastically elevated when the binding activity was reduced by deletion of four amino acids adjacent to the receptor binding site. Thus, a reciprocal relationship was observed between the receptor binding and the cell fusion activities of H1/USSR HA. No difference was observed, however, in lipid mixing activity, so-called hemifusion, between wild-type (WT) and oligosaccharide deletion mutant HAs. Soluble dye transfer testing showed that even the HA with the lowest cell fusion activity was able to form fusion pores through which a small molecule such as calcein could pass. However, electron microscopic studies revealed that a large molecule such as hemoglobin hardly passed through the fusion pores formed by the mutant HA, whereas hemoglobin did efficiently pass through those formed by the WT HA. These results suggested that interference in the process of dilation of fusion pores occurs when the binding of HA to the receptor is too tight. Since the viral nucleocapsid is far larger than hemoglobin, appropriate receptor binding affinity is important for virus entry.
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Millero, Frank J., i Sara Sotolongo. "PVT properties of concentrated aqueous electrolytes. 7. The volumes of mixing of the reciprocal salt pairs potassium chloride, potassium sulfate, sodium chloride, and sodium sulfate at 25.degree.C and I = 1.5 M". Journal of Chemical & Engineering Data 31, nr 4 (październik 1986): 470–72. http://dx.doi.org/10.1021/je00046a024.
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Esau, I., i S. Zilitinkevich. "On the role of the planetary boundary layer depth in the climate system". Advances in Science and Research 4, nr 1 (17.05.2010): 63–69. http://dx.doi.org/10.5194/asr-4-63-2010.
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Abstract. The planetary boundary layer (PBL) is a part of the Earth's atmosphere where turbulent fluxes dominate vertical mixing and constitute an important part of the energy balance. The PBL depth, h, is recognized as an important parameter, which controls some features of the Earth's climate and the atmospheric chemical composition. It is also known that h varies by two orders of magnitude on diurnal and seasonal time scales. This brief note highlights effects of this variability on the atmospheric near-surface climate and chemical composition. We interpret heat capacity parameter of a Budyko-type energy balance model in terms of quasi-equilibrium h. The analysis shows that it is the shallowest, stably-stratified PBL with the smallest h that should be of particular concern for climate modelling. The reciprocal dependence between the PBL depth and temperature (concentrations) is discussed. In particular, the analysis suggests that the climate characteristics during stably stratified PBL episodes should be significantly more sensitive to perturbations of the Earth's energy balance as well as emission rates. On this platform, h from ERA-40 reanalysis data, the CHAMP satellite product and the DATABASE64 data were compared. DATABASE64 was used to assess the Troen-Mahrt method to determine h through available meteorological profile observations. As it has been found before, the shallow PBL requires better parameterization and better retrieval algorithms. The study demonstrated that ERA-40 and CHAMP data are biased toward deeper h in the shallow polar PBL. This, coupled with the scarcity of in-situ observations might mislead the attribution of the origins of the Arctic climate change mechanisms.
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Thomalla, S. J., H. N. Waldron, M. I. Lucas, J. F. Read, I. J. Ansorge i E. Pakhomov. "Phytoplankton distribution and nitrogen dynamics in the Southwest Indian subtropical gyre and Southern Ocean Waters". Ocean Science Discussions 7, nr 4 (23.07.2010): 1347–403. http://dx.doi.org/10.5194/osd-7-1347-2010.
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Abstract. During the 1999 Marion Island Oceanographic Survey (MIOS 4) in late austral summer, a northbound and reciprocal southbound transect were taken along the Southwest Indian and Madagascar Ridge, between the Prince Edward Islands and 31° S. The sections crossed a number of major fronts and smaller mesoscale features and covered a wide productivity spectrum from subtropical to subantarctic waters. Associated with the physical survey were measurements of size fractionated chlorophyll, nutrients and nitrogen (NO3, NH4 and urea) uptake rates. Subtropical waters were characterised by low concentrations (<0.27 mg m−3) of pico-phytoplankton cells (>81%) and very low f-ratios (<0.1), indicative of productivity based almost entirely on recycled ammonium and urea. Diatom growth was limited by the availability of NO3 (<1 mmol m-3) and SiO4 (<1.5 mmol m−3) through vertical stratification that prevents the upward flux of nutrients into the euphotic zone. Biomass accumulation of small cells was likely controlled by microzooplankton grazing. In subantarctic waters, total chlorophyll concentrations increased (<0.74 mg m−3) and larger cells became more prevalent, however smaller phytoplankton cells and low f-ratios (>0.15) still dominated, despite sufficient NO3 availability. The results from this study favour Si limitation, light-limited deep mixing and likely Fe deficiency as the dominant mechanisms controlling significant new production by micro-phytoplankton. Increased concentrations of micro-phytoplankton cells and and rates of new production did however occur at oceanic frontal regions (58.6% and 11.22%, respectively), and in the region of the Prince Edward archipelago (61.4% and 14.16%, respectively). Here water column stabilization and local Fe-enrichment are thought to stimulate phytoplankton growth rates, especially of diatoms. Open ocean regions such as these provide important areas for local but significant POC export and biological CO2 draw-down in an overall HNLC Southern Ocean.
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Mirebeau, Isabelle, Sylvain Petit, Julien Robert, Solene Guitteny, Arsen Gukasov, Pierre Bonville, Andrew Sazonov i Claudia Decorse. "Magnetic structures and anisotropic excitations in Tb2Ti2O7spin liquid". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C1543. http://dx.doi.org/10.1107/s2053273314084563.
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Geometrical frustration in the pyrochlore lattice of corner sharing tetrahedra yields exotic short range ordered ground states known as spin liquids or spin ices. Among them, Tb2Ti2O7 spin liquid (also called quantum spin ice) remains the most mysterious, in spite of 15 years of intense investigation. Our recent single crystal experiments using neutron diffraction and inelastic scattering down to 50 mK yield new insight on this question. By applying a high magnetic field along a [111] anisotropy axis [1], the Tb moments reorient gradually without showing the magnetization plateau observed in classical spin ices. Quantitative comparison with mean field calculation supports a dynamical symmetry breaking akin to a dynamic Jahn-Teller distortion, preserving the overall cubic symmetry. In the non-Kramers Tb ion this induce a quantum mixing of the wave-functions of the ground state crystal field doublet enabling the formation of a spin liquid, viewed as a non-magnetic two-singlet ground state in this mean-field picture [2]. The spin lattice coupling also shows up in the spin fluctuations in zero field [3]. Dispersive excitations emerge from pinch-points in the reciprocal space, with anisotropic spectral weight. This is the first evidence of them in a disordered ground state. They reveal the breaking of some conservation law ruling the relative orientations of the fluctuating magnetic moments in a given tetrahedron, as for the monopole excitations in classical spin ices. The algebraic character of the correlations shows that Tb2Ti2O7 ground state is akin to a Coulomb phase. Finally, the first excited crystal field level and an acoustic phonon mode interact, repelling each other. The whole results show that the magnetoelastic coupling is a key feature to understand the surprising spin liquid ground state. They call for an interaction between quadrupolar moments, whose Jahn-Teller distortion is the first (single site) approximation.
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Kato, Yoshihito, Setsuro Hiraoka, Yutaka Tada, Kimihito Hirose i Jochen Büchs. "Mixing Performance of a Reciprocally Shaking Vessel". JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 36, nr 6 (2003): 663–67. http://dx.doi.org/10.1252/jcej.36.663.
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Lapere, Rémy, Laurent Menut, Sylvain Mailler i Nicolás Huneeus. "Seasonal variation in atmospheric pollutants transport in central Chile: dynamics and consequences". Atmospheric Chemistry and Physics 21, nr 8 (28.04.2021): 6431–54. http://dx.doi.org/10.5194/acp-21-6431-2021.
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Abstract. Central Chile faces atmospheric pollution issues all year long as a result of elevated concentrations of fine particulate matter during the cold months and tropospheric ozone during the warm season. In addition to public health issues, environmental problems regarding vegetation growth and water supply, as well as meteorological feedback, are at stake. Sharp spatial gradients in regional emissions, along with a complex geographical situation, make for variable and heterogeneous dynamics in the localization and long-range transport of pollutants, with seasonal differences. Based on chemistry–transport modeling with Weather Research Forecasting (WRF)–CHIMERE, this work studies the following for one winter period and one summer period: (i) the contribution of emissions from the city of Santiago to air pollution in central Chile, and (ii) the reciprocal contribution of regional pollutants transported into the Santiago basin. The underlying 3-dimensional advection patterns are investigated. We find that, on average for the winter period, 5 to 10 µg m−3 of fine particulate matter in Santiago come from regional transport, corresponding to between 13 % and 15 % of average concentrations. In turn, emissions from Santiago contribute between 5 % and 10 % of fine particulate matter pollution as far as 500 km to the north and 500 km to the south. Wintertime transport occurs mostly close to the surface. In summertime, exported precursors from Santiago, in combination with mountain–valley circulation dynamics, are found to account for most of the ozone formation in the adjacent Andes cordillera and to create a persistent plume of ozone of more than 50 ppb (parts per billion), extending along 80 km horizontally and 1.5 km vertically, and located slightly north of Santiago, several hundred meters above the ground. This work constitutes the first description of the mechanism underlying the latter phenomenon. Emissions of precursors from the capital city also affect daily maxima of surface ozone hundreds of kilometers away. In parallel, cutting emissions of precursors in the Santiago basin results in an increase in surface ozone mixing ratios in its western area.
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Thomalla, S. J., H. N. Waldron, M. I. Lucas, J. F. Read, I. J. Ansorge i E. Pakhomov. "Phytoplankton distribution and nitrogen dynamics in the southwest indian subtropical gyre and Southern Ocean waters". Ocean Science 7, nr 1 (8.02.2011): 113–27. http://dx.doi.org/10.5194/os-7-113-2011.
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Abstract. During the 1999 Marion Island Oceanographic Survey (MIOS 4) in late austral summer, a northbound and reciprocal southbound transect were taken along the Southwest Indian and Madagascar Ridge, between the Prince Edward Islands and 31° S. The sections crossed a number of major fronts and smaller mesoscale features and covered a wide productivity spectrum from subtropical to subantarctic waters. Associated with the physical survey were measurements of size fractionated chlorophyll, nutrients and nitrogen (NO3, NH4 and urea) uptake rates. Subtropical waters were characterised by low chlorophyll concentrations (max = 0.27.3 mg m−3 dominated by pico-phytoplankton cells (> 81%) and very low f-ratios (< 0.1), indicative of productivity based almost entirely on recycled ammonium and urea. Micro-phytoplankton growth was limited by the availability of NO3 (< 0.5 mmol m−3 and Si(OH)4 (< 1.5 mmol m−3 through strong vertical stratification preventing the upward flux of nutrients into the euphotic zone. Biomass accumulation of small cells was likely controlled by micro-zooplankton grazing. In subantarctic waters, total chlorophyll concentrations increased (max = 0.74 mg m−3 relative to the subtropical waters and larger cells became more prevalent, however smaller phytoplankton cells and low f-ratios (< 0.14) still dominated, despite sufficient NO3 availability. The results from this study favour Si(OH)4 limitation, light-limited deep mixing and likely Fe deficiency as the dominant mechanisms controlling significant new production by micro-phytoplankton. The percentage of micro-phytoplankton cells and rates of new production did however increase at oceanic frontal regions (58.6% and 11.22%, respectively), and in the region of the Prince Edward archipelago (61.4% and 14.16%, respectively). Here, water column stabilization and local Fe-enrichment are thought to stimulate phytoplankton growth rates. Open ocean regions such as these provide important areas for local but significant particulate organic carbon export and biological CO2 draw-down in an overall high nutrient low chlorophyll Southern Ocean.
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Ding, Weitian, Urumu Tsunogai, Fumiko Nakagawa, Takashi Sambuichi, Hiroyuki Sase, Masayuki Morohashi i Hiroki Yotsuyanagi. "Tracing the source of nitrate in a forested stream showing elevated concentrations during storm events". Biogeosciences 19, nr 13 (11.07.2022): 3247–61. http://dx.doi.org/10.5194/bg-19-3247-2022.
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Abstract. To clarify the source of nitrate increased during storm events in a temperate forested stream, we monitored temporal variation in the concentrations and stable isotopic compositions including Δ17O of stream nitrate in a forested catchment (KJ catchment, Japan) during three storm events: I, II, and III (summer). The stream showed a significant increase in nitrate concentration, from 24.7 to 122.6 µM, from 28.7 to 134.1 µM, and from 46.6 to 114.5 µM, during the storm events I, II, and III, respectively. On the other hand, the isotopic compositions (δ15N, δ18O, and Δ17O) of stream nitrate showed a decrease in accordance with the increase in the stream nitrate concentration, from +2.5 ‰ to −0.1 ‰, from +3.0 ‰ to −0.5 ‰, and from +3.5 ‰ to −0.1 ‰, for δ15N; from +3.1 ‰ to −3.4 ‰, from +2.9 ‰ to −2.5 ‰, and from +2.1 ‰ to −2.3 ‰ for δ18O; and from +1.6 ‰ to +0.3 ‰, from +1.4 ‰ to +0.3 ‰, and from +1.2 ‰ to +0.5 ‰, for Δ17O during the storm events I, II, and III, respectively. Besides, we found strong linear relationships between the isotopic compositions of stream nitrate and the reciprocal of stream nitrate concentrations during each storm event, implying that the temporal variation in the stream nitrate can be explained by simple mixing between two distinctive endmembers of nitrate having different isotopic compositions. Furthermore, we found that both concentrations and the isotopic compositions of soil nitrate obtained in the riparian zone of the stream were plotted on the nitrate-enriched extension of the linear relationship. We concluded that the soil nitrate in the riparian zone was primarily responsible for the increase in stream nitrate during the storm events. In addition, we found that the concentration of unprocessed atmospheric nitrate in the stream was stable at 1.6 ± 0.4, 1.8 ± 0.4, and 2.1 ± 0.4 µM during the storm events I, II, and III, respectively, irrespective of the significant variations in the total nitrate concentration. We concluded that the storm events have fews impacts on the concentration of unprocessed atmospheric nitrate in the stream, and thus the annual export flux of unprocessed atmospheric nitrate relative to the annual deposition flux can be a robust index to evaluate nitrogen saturation in forested catchments, irrespective to the variation in the number of storm events and/or the variation in the elapsed time from storm events to sampling.
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Bishop, Clifton P., i Theodore R. F. Wright. "Ddcde1, a Mutant Differentially Affecting Both Stage and Tissue Specific Expression of Dopa Decarboxylase in Drosophila". Genetics 115, nr 3 (1.03.1987): 477–91. http://dx.doi.org/10.1093/genetics/115.3.477.
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ABSTRACT The isolation and characterization of a unique Dopa decarboxylase (Ddc) mutant in Drosophila melanogaster is reported. This mutant, Ddcde1, exhibits stage- and tissue-specific altered Ddc expression. Homozygous Ddcde1 embryos, central nervous systems (CNSs) at pupariation and newly eclosed adult epidermis all have approximately 5% as much specific dopa decarboxylase (DDC) activity as the pr control stock in which Ddcde1 was induced. In contrast, the Ddcde1 epidermis at pupariation has roughly 50% as much DDC activity as controls, a 10-fold increase over the relative activity detected in other tissues and stages. Although the adult cuticle lacks proper pigmentation as expected in flies with low DDC activity (?5%), the bristles unexpectedly have wild-type black pigmentation. This implies that the bristle forming cells have more DDC activity than the rest of the adult epidermis. This variegated phenotype, black bristles and pale cuticle, plus the fact that Ddcde1 was originally isolated in a reciprocal translocation between proximal X heterochromatin and the euchromatic left arm of the second chromosome, 42 bands from the Ddc locus, suggested that the mutant might be an example of position-effect variegation. All tests for position-effect variegation, including persistence of the mutant phenotype when Ddcde1 was removed from the translocation, were negative. At pupariation DDC cross-reacting material (CRM) levels are similar in Ddcde1 and wild-type controls, but in newly eclosed adults CRM levels are approximately 35% of wild-type controls. This suggests that DDC produced by Ddcde 1 adults has less activity per DDC molecule than the DDC produced at pupariation by Ddcde1. If the DDC enzyme produced by Ddcde1 at adult eclosion had full DDC activity (35% DDC CRM = 35% DDC activity) then no mutant phenotype would be exhibited by Ddcde1 since flies with as little as 10% activity have a wild-type phenotype. DDC thermolability assays clearly demonstrate that DDC from Ddcde1 is more thermolabile than control DDC at both pupariation and adult eclosion. Furthermore, DDC from adults in both Ddcde1 and the pr control is more thermolabile than DDC from white prepupae. Mixing experiments indicate the difference in DDC thermolability between pr white prepupae and pr adults is not due to a difference in the white prepupal and adult supernatants. This suggests that in wild-type different isoforms of DDC are produced either by differences in post-translational modification or as a result of a different primary amino acid sequence. The lesion in Ddcde1 may be in a translated sequence which is more important for proper Ddc expression in embryos, CNSs at pupariation and adult epidermis than it is in white prepupal epidermis and the bristle-forming cells.
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Edwards, P. M., M. J. Evans, K. L. Furneaux, J. Hopkins, T. Ingham, C. Jones, J. D. Lee i in. "OH reactivity in a South East Asian Tropical rainforest during the Oxidant and Particle Photochemical Processes (OP3) project". Atmospheric Chemistry and Physics Discussions 13, nr 2 (22.02.2013): 5233–78. http://dx.doi.org/10.5194/acpd-13-5233-2013.
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Abstract. OH reactivity, the reciprocal of its lifetime from reaction with its sinks, was measured for 12 days in April 2008 within a tropical rainforest on Borneo as part of the OP3 project. The maximum observed value was 83.8 &pm; 26.0 s−1 with the campaign averaged noon-time maximum being 29.1 &pm; 8.5 s−1. The maximum OH reactivity calculated using the campaign averaged noon-time concentrations of observed sinks was ~18 s−1, significantly less than the observations, consistent with other studies in similar environments. OH reactivity was dominated by reaction with isoprene. Numerical simulations of isoprene oxidation using the Master Chemical Mechanism (v3.2) in a highly simplified physical and chemical environment show that the steady state OH reactivity is a linear function of the OH reactivity due to isoprene alone, with a maximum multiplier being equal to the number of isoprene OH attackable bonds (10). Thus the emission of isoprene constitutes a significantly larger emission of reactivity than is offered by the primary reaction with isoprene alone, with significant scope for the secondary oxidation products of isoprene to constitute the missing reactivity. A physically and chemically more sophisticated simulation (including physical loss, photolysis, and other oxidants) showed that the calculated OH reactivity is reduced by the removal of the OH attackable bonds by other oxidants and photolysis, and by physical loss (mixing and deposition). The calculated OH reactivity is increased by peroxide cycling, and by the OH concentration itself. Notable in these calculations is that the lifetime of OH reactivity is significantly longer than the lifetime of isoprene and critically depends on the chemical and physical lifetime of intermediate species. When constrained to the observed campaign averaged diurnal concentrations of primary volatile organic compounds (VOCs), O3, nitrogen oxides (NOx) and other parameters, the model underestimated the observed mean OH reactivity by 30%. However, it was found that: (1) the short lifetimes of isoprene and OH lead to a large variability in their concentrations and so significant variation in the calculated OH reactivity, (2) uncertainties in the OH chemistry in these high isoprene environments can lead to an underestimate of the OH reactivity, and (3) the physical loss of species that react with OH plays a significant role in the calculated OH reactivity, (4) a missing primary source of reactive carbon would have to be emitted at a rate equivalent to 50% that of isoprene to account for the missing OH sink. A clear argument for a significant missing flux of primary emitted VOC compounds to account for the unmeasured reactivity is not found and the development of techniques for the measurement of secondary multifunctional carbon compounds is needed to close the OH reactivity budget.